Stabilization of diphenylaminechlorarsine gas generating charges by coating the particles with a drying oil



United States Patent O 3,085,047 STABILIZATION OF DIPHENYLAMINECHLORAR- SINE GAS GENERATING CHARGES BY COAT- ING THE PARTICLES WITH A DRYING OIL Carl R. Weinert, Pittsburgh, Pa., assignor to Federal Laboratories, Inc., Saltsburg, Pa., a corporation of Penn- Sylvania Filed Oct. 13, 1960, Ser. No. 62,217 8 Claims. (Cl. 167-47) The present invention relates to the manufacture of a gas grenade or other device having stabilized diphenylaminechlorarsine included in the gas-generating charge thereof, and to the method of so stabilizing that charge for producing lengthened surveillance life of the grenade. When ignited, the device produces a cloud of toxic smoke with or without an accompanying amount of irritant such as tear gas in the cloud, depending, of course, on the selection of constituent materials desired for the purposes of the charge. These devices include but are not limited to grenades, projectiles, and bank and prison gun cartridges.

lt has been found in practice that toxic gas grenades or combined toxic and tear gas grenades have a limited useful shelf life, not because of their failure with aging to thereafter generate gas when iired, but because, by then, the burning time will have slowed down too much for the grendaes to be effective if, in fact, they can be relied upon at all and at the same time be predictable with some degree of accuracy. Therefore, it is the practice to periodically replace the different stocks of toxic or combination grenades in prisons and in government and police arsenals. The reasons for fast burning and rapid gas evolution are practical-one having to do with the surprise factor of an overwhelming amount of gas being developed all at once, which is a big element in dispersing a mob of rioters. Moreover, an accelerated rate of burning enabling a grenade to expend itself is a great deterrent against having a grenade tossed away by the rioters or, worse, tossed back.

In the gas cloud produced by a grenade according to the present invention, the toxic agent is a sternutatory (sneeze gas) material consisting of vaporized diphenylaminechlorarsine. It liberates as a nausea-causing cloud when commercial diphenylaminechlorarsine is vaporized by means of a nitrocellulose fuel present in the charge, preferably smokeless powder. Due to the stabilizer provided according to the present invention, the age-deterioration process of the charge or, more especially, of the smokeless powder is delayed sufficiently to materially increase the surveillance life.

More particularly, in the preparation of the diphenylaminechlorarsine of the present charge, a stabilizer is mixed with the commercial diphenylaminechlorarsine prior to the time at which the anti-acid and the tear gas material, if any, and fuel are added and admixed therewith. When this mixture is charged into the finished gas grenade casing, the result is a delay of the perceptible aging as long as practicably desirable so far as burning time is concerned; replacement of the charges can safely be delayed many months longer than before.

The foregoing advantages are accomplished by the stabilized charge and means of stabilizing it which comprise my invention, as will now be explained. Features, objects and further advantages are either specifically explained or will become apparent when, for a better understanding of the invention, reference is made to the accompanying drawing which forms a part hereof and in which:

FIGURE 1 is a block flow diagram of the manufacture of a gas grenade according to the present invention;

3,085,047 Patented Apr. 9, 1963 ICC FIGURE 2 shows a modified part of the ow diagram of FIGURE 1; and

FIGURE 3 is a graph of comparative performances showing grenade discharge time plotted against the grenade age.

More particularly, in reference 'to the drawing, a manufacture ow sheet according to a preferred embodiment of the invention takes the appearance of FIGURE 1. It involves the following steps:

Step I: A quantity of dry commercial-grade (crude) diphenylaminechlorarsine particles and a quantity of a stabilizer in liquid or molten form, or as a solution, are placed in a commercial Globe mixer and thoroughly mechanically mixed so as to coat the particles. The purpose of the stabilizer is to form a continuous coat or lm impermeable to and mutually insoluble with diphenylamine, diphenylaminechlorarsine and smokeless powder. In the case of the stabilizer being introduced in molten form, the coat, on cooling, may stick the particles together, in which case grinding will be necessary to break their adherence.

Step II: In case the coat is a liquid stabilizer, such as an appropriate drying oil, or else a stabilizer in solution form, the damp particles leaving the mixer '10 are introduced to and kept upon drying trays 12 for a day or for a few days in order to properly dry. The particles are thus stabilized.

Step III: The stabilized particles, together with an anti-acid and a quantity of fuel, are introduced into a rotating bottle mixer indicated at 14, the bottles of which are covered to prevent contamination. Mixing within the bottles produces a loose, dry mix. The proportions of the mixture are such that it contains by weight 50% to of the nitrocellulose fuel, 5% to 10% of precipitated chalk (CaCO3) as the anti-acid material, and the balance stabilized diphenylaminechlorarsine.

I Step IV: The dry mix is introduced and compressed into a grenade case by an operation indicated at 16. The compression pressure is quite high, running to a figure approximately between 1 and 2 tons per square inch.

Step V: rl`he iinal assembly operation for the grenade is indicated by the reference numeral 18. The finished gas grenade is indicated at 20 in FIGURE l, incorporating the stabilized charge.

Examples which follow of specific ways of accomplishing the stabilization included in the foregoing steps are intended to illustrate the invention for a better understanding. They are by no means exhaustive of the ways possible, being disclosed with the desired purpose of a fuller description and not of limitation.

Examples Several parts of diphenylaminechlorarsine powder of commercial grade having a particle size which pass a 20- mesh screen are added in the foregoing Step I for each part of the stabilizer liquid consisting of boiled linseed oil. The amount of the linseed oil is sufficient to give the mixture the consistency of damp sand, the actual proportions being such that the ratio of diphenylaminechlorarsine to linseed oil therein ranges from 11:1 to 7:1 by weight, with the preferred ratio being 9:1.

The damp mix, in accordance with foregoing Step II, is placed on drying trays and air-dried. Boiled linseed oil, when completely exposed to the air, is known to dry completely hard in 24 hours; but the preferred time of drying is several days in Step II hereof. It is a characteristic of this particular drying oil that it is absorbed sufficiently that the particles do not stick together; in view of this noncohesive characteristic, no grinding apart of the dried particles is necessary. At this point, the oxidized oil is a continuous lm around each particle of the diphenylaminechlorarsine so as to be impervious thereto as a barrier isolating the diphenylaminechlorarsine and its impurities from the smokeless powder fuel added according to foregoing Step III.

If the boiled linseed oil is applied as a coat to the fuel instead of to the diphenylaminechlorarsine, whereafter the coated fuel and the diphenylaminechlorarsine are mixed, the charge is the same `as hereinabove from standpoint of shelf stability; however, there is a noticeably undesirable sacrifice of economy due to the added amount of linseed oil required for the bulk of the fuel.

If parafiin is substituted for linseed oil as the stabilizer, resulting in a step which can be identified as Step IA, then this corresponding step differs to the extent that the parain or other appropriate solid hydrocarbon is preferably melted and applied in the mixer to the diphenylaminechlorarsine so as to coat the powder particles before the hydrocarbon cools. In those instances, the dry mix operation becomes a modified Step IIIA, because of the disadvantage posed that the charge will require a greater proportion of fuel to be added in such Step IIIA. The step requires more of the nitrocellulose fuel because the barrier coat of hydrocarbon must also be vaporized during the firing of the charge.

If natural waxes, such as copal, beeswax, or the like, or if synthetic resins (e.g., polyethylene or polystyrene) are used as the substitute stabilizer in a further modified step which can be identified as Step IB, then in those instances they can be added either in molten state or added in solution of which turpentine or alcohol, for example, is the solvent. In either case, they dry to form the impervious stabilizer coat on the diphenylaminechlorarsine particles of powder.

A manufacture flow chart, illustrative of a preferred embodiment of the invention for combined grenades, takes the appearance in part of FIGURE 2. It includes the foregoing Steps I and II, but the next step is a modified Step IIIC which introduces the tear gas material at the same time at which the fuel and other substances are added preparatory to the dry mixing Step IV. Step IV and Step V are the same as before.

In FIGURE 2, the anti-acid is indicated as added at 22 and consists of precipitated chalk, as before. Also added is the tear gas material chloracetophenone identified as CN. The precipitated chalk will also stabilize the CN. The diphenylaminechlorarsine stabilized in the manner of the preceding description is indicated by the block 26 and fuel is indicated by the double block 28, which is doubled in the drawing merely to indicate more of the same fuel. In other words, some larger amount of such nitrocellulose fuel 28 is required in this instance to be added in the mixing operation, indicated at 30, because of the additional fuel required in this instance to vaporize the tear gas material CN.

Again, the proportions of the charge resulting from the mixing operation 30 are such that the ratio of materials contained is 50% to 80% of the nitrocellulose fuel, 5% to composed of the block 22 of anti-acid, and the balance consisting of the stabilized diphenylaminechlorarsine and the CN material. This balance has proportions such that the ratio of stabilized toxic gas producing material to the tear gas producing material ranges between 4:1 and 1:4 by weight for proper effectiveness of each gas constituent in the blended cloud of gas. A grenade so charged is referred to herein as a combined grenade.

For comparison purposes, two groups of samples of a standard No. 113 toxic gas grenade were made and thereafter tested at intervals, one group being conventional and the other group being made according to the procedure above outlined employing boiled linseed oil as the stabilizer. The burning time performance of the stabilized grenades, when plotted, takes the appearance of the lower curve 32 according to FIGURE 3. It is seen that no substantial aging process is manifest over a course of months or, in fact, two or more years time. On the other hand, the performance of the group of existing type grenade as to burning time takes the appearance of th upper curve 34, from which it can be noted that deterioration with age is sustained as a continuous process with no particular arresting point evident over a course of months or years. During progress of the tests, the trend of each group was so apparent that the tests -were discontinued after approximately two years.

The significance of ythe stabilized low burning time for the improved grenades according to the curve 32 is that, once ignited, the time interval for re-tossing or tampering with these grenades as a practical matter is too short and a presently improved grenade two years old or older can be relied upon `to rapidly expend itself once ignited with Ilittle chance of meantime being disturbed by human hands.

No reason has been exhaustively explored and is known as to why the surveillance life (storage life) has heretofore been limited comparatively drastically. A working hypothesis, however, has been advanced based on chemical considerations of the ingredients of the charge both before and after being introduced into the grenade as finished.

The toxic gas producing material diphenylaminechlorarsine in pure state, hereinafter referred to as pure DM((C6H4)2NHAsCl), has the following structural formula:

Diphenylaminechlor-arsine is never pure commercially like the 4above structural formula shows. Only about 70% to is the pure DM and the balance consists of impurities, the presence of which is most readily understood from considering one of the commerical ways of producing diphenylaminechlorarsine. The starting material is diphenylamine (C6H5NHC6H5) which is reacted with arsenic trichloride, producing hydrochloric acid along with the wanted diphenylaminechlorarsine as follows:

It is thus seen that hydrochloric acid is present which is not removed from the commercial diphenylaminechlorarsine.

The reason for presence of another impurity is due to the fact that Equation 2 -above is not irreversible and, in addition to the unreacted diphenylamine, if any, which is present, there is an equilibrium point reached in the reverse direction accounting for the presence of further of the diphenylamine as follows:

The equilibrium quantity of the arsenic trichloride of chemical Equation 3 and any excess of the arsenic trichloride still present in the commercial production (i.e., that which is unreacted) do not to any material degree remain present in -the commercial grade as such; any substantial -amount will gradually hydrolize as follows:

Each underscored item in the right-hand side of foregoing Equations 2, 3 and 4 is present in each grain of the powder of diphenylaminechlorarsine, of which, as above indicated, the pure DM constitutes only 70% to 901% by weight, with the balance of 30%-10% being composed of the arsenic trioxide (As2O3), diphenylamine, and hydrochloric acid plus the separate particles of chalk (CaCO3) later added as anti-acid, as already described.

Of these impurities and the additive, it is believed that the stabilizing barrier on the particles of the diphenylaminechlorarsine is impermeable to and mutually insoluble with the diphenylamine and is inert insofar as chemically attacking or lbeing chemically attacked by the diphenylamine. The reason for isolating the particles of crude diphenylaminechlorasine with a coat is additionally believed necessary because the pure DM content therein tends to break down, analogously to Equation 4 by hydrolizing or for other reasons, over a period of months or years so as to further supplement the quantity of diphenylamine. The extreme imperviousness of the coat to' the diphenylamine in particular is felt to account yfor the fuel being retained in a fast burning status without physical impairment upon aging while in the charge.

In other respects, the impurities which might impair or attack the fuel can generally be accounted for, one item being the arsensic which, of course, as above indicated, hydrolizes into a fairly inert oxide. The presence of the anti-acid chalk insures that the hydrochloric acid, if it escapes from inside .the particles in any quantity, will be automatically neutralized as follows:

For this reason, the chalk is commonly referred to in the grenade field as a stabilizer.

From the foregoing, it is seen that the practice of the present inventions in the manufacture of a toxic gas charge is such that, except for a barely perceptible trend in lthe first few months, the charges stabilize as rto burning time so that to be consistent over the course of months up to three or four years or more. This advantage leads to much greater reliability for prison, police, and armed service work, and to considerable gains in economy because of the longer available surveillance life of the present gas grenade. An altogether unexpected result of the stabilizer coat has particular significance. That is to say, despite the presumed barrier of an inert coat of oxidized Stabilizer thereabout, the particles are consistently vaporized faster by the fuel in present grenades even when fired fresh. This fact is evidenced by the comparative curves of FIGURE 3 from which the burning time is readily seen to have been speeded up at all points along the curve 32 relative to the reference curve 34 as plotted for grenades with uncoated diphenylaminechlorarsine particles.

Variations within .the `spirit and scope of the inventions described are equally comprehended by the foregoing description.

I claim:

1. In the method of preparing a gas generating charge, the steps comprising coating diphenylaminechlorarsine particles with an impermeable film of stabilizing agent r and thereafter mixing the stabilized diphenylaminechlorarsine particles with a fuel.

2. In the method of preparing a gas generating charge, the steps comprising mixing diphenylaminechlorarsine particles with a drying oil, drying the mixture in air to coat the individual diphenylaminechlorarsine particles with an impermeable film of oxidized drying oil, and thereafter mixing the stabilized diphenylaminechlorarsine particles with a fuel.

3. In the method of preparing .a gas generating charge, the steps comprising mixing diphenylaminechlorarsine particles with linseed oil, drying `the mixture in air to coat the individual diphenylaminechlorarsine particles with an impermeable film of oxidized linseed oil, and thereafter mixing the stabilized diphenylaminechlorarsine particles with a fuel.

4. In .the method of preparing a gas generating charge, the steps comprising mixing diphenylaminechlorarsine particles with linseed oil, drying the mixture in air to coat the individual diphenylaminechlorarsine particles with an impermeable film of oxidized linseed oil, and thereafter mixing the stabilized diphenylaminechlorarsine particles with a fuel and an anti-acid agent.

5. A method according to claim 4, wherein the antiacid agent is precipitated chalk.

6. In the method of preparing a gas generating charge, the steps comprising mixing diphenylaminechlorarsine particles with linseed oil, drying; the mixture in air Ito coat the individual diphenylaminechlorarsine particles with an impermeable ltilm of oxidized linseed oil, and thereafter mixing the stabilized diphenylaminechlorarsine particles with a fuel, chloracetophenone and an anti-acid agent.

7. A gas generating charge consisting essentially, by weight, of -S0% nitrocellulose particles, 510% of an anti-acid agent, and the balance of diphenylaminechlorarsine particles each coated with an impermeable film of oxidized drying oil, the nitrocellulose particles being uncoated.

8. A gas generating charge consisting essentially, by weight, of 50-80% nitrocellulose particles, chloracetophenone particles, 5-l0% of an antiacid agent, and the balance of diphenylaminechlorarsine particles each coated with an impermeable film of oxidized drying oil, the nitrocellulose particles being uncoated.

References Cited in the tile of this patent UNITED STATES PATENTS 1,864,754 Oglesby et al lune 28, 1932 1,878,488 Goss Sept. 20, 1932 2,155,499 Lawson Apr. 25, 1939 2,916,996 Coffee Dec. l5, 1959 FOREIGN PATENTS 25,711 Great Britain Jan. 30, 1897 

1. IN THE METHOD OF PREPARING A GAS GENERATING CHARGE, THE STEPS COMPRISING COATING DIPHENYLAMINECHLORARSINE PARTICLES WITH AN IMPERMEABLE FILM OF STABILIZING AGENT AND THEREAFTER MIXING THE STABILIZED DIPHENYLAMINECHLORARSINE PARTICLES WITH A FUEL
 8. A GAS GENERATING CHARGE CONSISTING ESSENTIALLY, BY WEIGHT, OF 50-80% NITROCELLULOSE PARTICLES, CHLORACETOPHENONE PARTICLES, 5-10% OF AN ANTI-ACID AGENT, AND THE BALANCE OF DIPHENYLAMINECHLORARSINE PARTICLES EACH COATED WITH AN IMPERMEABLE FILM OF OXIDIZED DRYING OIL, THE NITROCELLULOSE PATICLES BEING UNCOATED. 